1. Field of the Invention
The present invention relates to a brake control system for an electrically operated vehicle to perform a regenerative braking operation and a hydraulic braking operation, and more particularly to the brake control system which is adapted to reduce a regenerative braking torque and add a hydraulic braking force to compensate for a lack of regenerative braking torque, smoothly.
2. Description of the Related Arts
In an electrically operated vehicle provided with an electric motor as a power source, the electric motor also functions as a generator for performing the regenerative braking operation to recover energy by charging a battery and use the energy for driving the motor. Since the braking force applied to the vehicle wheels through the regenerative braking operation is limited, a lack of braking force must be compensated by the hydraulic braking operation for example. Therefore, both of the regenerative braking operation and the hydraulic braking operation are performed, as disclosed in Japanese Patent Laid-open Publication No. 5-161210. According to the prior brake control system for the electrically operated vehicle as disclosed in the Publication No. 5-161210, the regenerative braking torque is set in accordance with a predetermined torque map or hydraulic pressure coefficient, and a lack of regenerative braking torque, which is caused in a relatively low speed range for example, is compensated by the hydraulic braking operation or the like. However, since the hydraulic braking force to be compensated is varied, the amount of regenerative braking torque to be compensated may be excessive occasionally. In this case, feelings to a vehicle driver in his braking operation will be varied.